As for conventional wireless communication apparatuses, in recent years, the Wireless Lan cards designed according to IEEE 802.11 protocol can be found at the market easily. The Wireless Lan card can be installed in a common personal computer (PC) or a portable computer. Via an access point (AP), the Wireless Lan card can communicate with a wired data network so that a user can use the Wireless Lan card to surf the network in a wireless manner.
In the recent development of the radio systems, the main issues include: QoS maintenance between different radio systems, management of radio modules, seamless handoff between radio system design for the beyond third generation (B3G) network.
In the field of QoS, some organizations are trying to define their own standards for radio systems, e.g. IEEE 802.11E protocol for wireless local area networks (WLAN), 3GPP TS23.107 for wideband code division multiple access (WCDMA) systems, etc. However, most of these standards are defined with individual QoS criteria adapted for their own wireless network structures. These standards only can guarantee a specific QoS at wireless terminals, but they can hardly support a QoS of wired networks. Hence, they can't satisfy the requirements of the end-to-end QoS.
In order to reach the end-to-end QoS guarantee, an interworking unit is usually used between different systems for communication and maintaining the QoS. However, different radio systems possess different network features and an additional interworking unit should be used for mapping the requirements of different QoS. Hence, this method is costly and easily induces the degradation of QoS during executing the mapping process.
As per seamless handoff, please refer to FIG. 1A, which is disclosed in “Enhanced handoff signaling for high speed data and multimedia,” U.S. Pat. No. 6,205,128. This patent discloses a mechanism for handoff while the radio communication system finds the signal is too weak to maintain the connection quality. Once handoff is needed, the source system will first inform the wireless apparatus. Then, the wireless apparatus will execute the handoff process when the target system is ready. Please also refer to FIG. 1B, which is disclosed in “Method and system for seamless handoff between radio networks with a mobile terminal,” U.S. Pat. No. 6,243,581. Some techniques can be used to search a more suitable radio link to make the wireless apparatus able to transfer data in the radio link with higher bandwidth after handoff.
As per multi-mode reconfigurable technology, please refer to FIG. 2, which illustrates an operation flowchart of a soft defined radio system mentioned in “Design and implementation of software framework for software defined radio system.” VTC 2002-Fall, Volume: 4, 2002. By employing the mechanism of the this system, a wireless communication apparatus will first measure the magnitude of received signals and then decide if the software and hardware modules should be changed to adapt to a different system. However, the problems about seamless handoff are not considered in this system architecture. Hence, the transmission of this system will be interrupted during the module changing process.
Moreover, in “Reconfigurable terminals: an overview of architectural solution,” IEEE Communications Magazine, to Vol. 39 Issue: 8, another system architecture designed in TRUST project of IST is introduced. This system architecture has mode monitoring, mode switching and software download mechanisms and reconfigurable baseband system structure. By employing this architecture, the mode monitoring mechanism will decide which radio system should be connected to when the wireless apparatus is actuated. Subsequently, the mode monitoring mechanism will decide if the wireless apparatus should be adjusted to connect with another system during its movement and then adjust the radio system via the mode switching and software download mechanisms. This reference paper also mentions the problem of service interruption occurred during mode switching due to there is only one wireless transceiver available in the hardware and recommends to employ two transceivers in the hardware to resolve this problem.
As per the radio system architecture beyond third generation, please refer to FIG. 3, a wireless application layer (WAL) is inserted between the network layer and the physical layer. The wireless application layer includes a WAL coordinator, a plurality of radio modules, a traffic control module and a logical link control translate module.
The WAL coordinator is used to recognize the networks the packets belong to and then invoke the radio modules to process the packets. Subsequently, the processed packets will he delivered to the traffic control module for scheduling. Finally, via the logical link control translate module, the packets will be passed to the physical layer for transmission. However, this system architecture is only suited to use in the radio systems with similar attributes, this system architecture can't be used to coordinate and communicate with the radio modules if the radio systems have completely different media access control mechanisms. Besides, this system architecture can't support seamless handoff due to this system architecture can only control a radio module at a time.
As mentioned above, in the prior art, QoS, multi-mode reconfigurable and seamless handoff mechanisms and system architecture beyond third generation have been proposed. However, the wire-line like QoS can't be reached by improving one or two of these techniques. For instance, real-time multimedia transmission can't be reached without QoS technique; the wireless apparatus can only transfer data in a single radio system without multi-mode reconfigurable technique and hence the wireless apparatus can't access the network anytime and anywhere; the QoS will be degraded and even interrupted during handoff process without seamless handoff technique.
Accordingly, as discussed above, the conventional wireless communication apparatuses still have some drawbacks that could be improved. The present invention aims to resolve the drawbacks in the prior art.